PreCalc
posted by Lauren on .
I am supposed to graph this
y= x^2+2x
he told us to coplete the square to get us the vertex, but how do i complete the square with a  in front of the x^2??

This way:
x^2 + 2 x = y
x^2  2 x = y
x^2  2 x + 1 = y+1
(x1)^2 = (y1)
vertex at (1,1)
negative sign means opens down (sheds water)